Shoulder joint replacement has been in use for many decades. The articular surfaces of the shoulder joint include a ball and a socket which may be damaged by trauma or degenerative disease. Pain and limitation of movement will require a replacement of the articular surfaces using a hemispherical humeral component and a shallow glenoid component. Damages to the rotator cuff and supporting structures will require the use of reverse shoulder implant, where the geometry of the components is reversed, and the humeral component is designed as a cupule while the hemispherical ball is attached to the glenoid plate.
However, the surgical procedure for the insertion of the prosthetic component requires significant surgical exposure that will unduly damage local anatomical structures such as surrounding muscles and adjacent tendon tendons. Said damage will impose longer healing period and require extensive postoperative physical therapy. However, both anatomical shoulder implants as well as more recent reverse implants are traditionally inserted through conventional surgical approach. Traditionally, the proximal humerus is reamed to allow for insertion of the stem of the humeral component. However, the existence of prior trauma and deformity of the proximal humerus preclude the use of implant with humeral stem. More recently, stem free or stemless humeral component are designed and used but remain bulky and require insertion through a conventional extensive surgical approach. The shoulder joint is anatomically a distraction joint as opposed to the hip knee and ankle joints which are weight bearing and compression joints. In the shoulder joint, compression forces are limited to lifting heavy objects when the arm is in the horizontal position. Conventionally used glenoid polyethylene components are known to flow and become loose leading to osteolysis.